College of Environmental Science, Sichuan Agricultural University, Wenjiang, 611130, China; Sichuan Provincial Key Laboratory of Soil Environmental Protection, Chengdu, 611130, China; Institute of Environmental Sciences (CML), Leiden University, P.O. Box 9518, 2300 RA, Leiden, the Netherlands.
College of Environmental Science, Sichuan Agricultural University, Wenjiang, 611130, China; Chengdu Agricultural College, Wenjiang, 611130, China.
Environ Res. 2020 Jul;186:109554. doi: 10.1016/j.envres.2020.109554. Epub 2020 Apr 19.
Biodegradable chelators (BCs) are promising substitutes for conventional washing agents in the remediation of heavy metal contaminated soil with strong complexing ability and less cost. However, great challenges for the applications of BC-assisted washing still exist, such as the assessment of the factor affecting the efficiency of metal removal and the unclear of the metal removal mechanism. Batch washing was therefore explored to evaluate the potential for four BCs for removing Cd, Pb, and Zn from polluted soils. The soil spectroscopic characteristics before and after washing were also investigated. The results demonstrated that iminodisuccinic acid (ISA) and glutamate-N, N-diacetic acid (GLDA) were an appealing alternative to commonly used non-biodegradable ethylenediaminetetraacetic acid, but glucomonocarbonic acid (GCA) and polyaspartic acid (PASP) were less efficient. Optimal parameters of BCs were determined to be a concentration of 50 mmol L, a pH of 5.0, a contact time of 120 min, and a solid/liquid ratio of 1:5, considering metal removal efficiencies and the suitable cost. A single removal washing could be up to 52.39% of Cd, 71.79% of Pb, and 34.13% of Zn from mine soil, and 98.28% of Cd, 91.10% of Pb, and 90.91% of Zn from polluted farmland soil. After washing, the intensity of heavy metal binding to soil colloids increased while the metal mobility reduced because of weakly bound fractions removed by BCs. The BCs-induced soil washing revealed that the possible mechanisms of metal removal included the acid dissolution, ion exchange, and surface complexation. Our findings highlight the potential application of especially ISA and GLDA as efficient washing agents to remove potentially toxic elements from contaminated soils.
可生物降解螯合剂 (BC) 具有很强的络合能力和较低的成本，是修复重金属污染土壤的传统洗涤剂的有前途的替代品。然而，BC 辅助洗涤的应用仍然存在很大的挑战，例如评估影响金属去除效率的因素和金属去除机制不明确。因此，进行了批处理洗涤以评估四种 BC 从污染土壤中去除 Cd、Pb 和 Zn 的潜力。还研究了洗涤前后土壤的光谱特征。结果表明，亚氨基二琥珀酸（ISA）和谷氨酸-N，N-二乙酸（GLDA）是常用的不可生物降解乙二胺四乙酸的有吸引力的替代品，但葡萄糖单羧酸（GCA）和聚天冬氨酸（PASP）的效率较低。考虑到金属去除效率和合适的成本，确定了 BC 的最佳参数为 50 mmol L 的浓度、pH 值为 5.0、接触时间为 120 min 和固液比为 1:5。单去除洗涤可从矿山土壤中去除高达 52.39%的 Cd、71.79%的 Pb 和 34.13%的 Zn，从污染农田土壤中去除高达 98.28%的 Cd、91.10%的 Pb 和 90.91%的 Zn。洗涤后，由于 BC 去除了弱结合部分，重金属与土壤胶体结合的强度增加，而金属的迁移性降低。BC 诱导的土壤洗涤表明，金属去除的可能机制包括酸溶解、离子交换和表面络合。我们的研究结果强调了 ISA 和 GLDA 作为有效洗涤剂从污染土壤中去除潜在有毒元素的潜在应用。
